1. Field of the Invention:
This invention relates to an apron for a draft apparatus which is suitable for use with a spinning machine, especially with a pneumatic high speed spinning frame and further to a method of producing the same.
2. Prior Art:
A draft apparatus is already known in the art in which, in order to draft slivers, such slivers are passed sequentially between a plurality of pairs of pressure contacted rollers, which are arranged such that they have gradually increasing circumferential speeds in the order as slivers advance. In such known draft apparatus, it is one of particularly serious problems how draft irregularities are reduced which have a worst effect on qualities of yarns, such as uniformity, strength, and so on.
In a draft apparatus of a three line type, such rollers as described above include back, middle and front roller pairs, and a belt commonly called an apron is mounted on each of rollers of the middle roller pair. One of causes of such irregularities as mentioned above is deformation of an apron due to wear. Particularly when compared with a spinning frame such as of the ring type in which a draft rate is low, a pneumatic spinning frame operates at a high speed and directly drafts slivers. Consequently, in a pneumatic spinning frame, the draft rate is very high and middle rollers are rotated also at a high speed, resulting in rapid progress of deformation of the middle rollers by wear.